Is This Head Gasket Blown?

Discussion in 'Technical Help' started by StuarT595, Jan 18, 2021.

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  1. StuarT595

    StuarT595 Active Member

    Nov 19, 2020
    204
    43
    South West UK
    I was told the head gasket was blown by a very experienced bike mechanic...difficult start, rough running, new thermostat cap already insitu, dirty orange water all over the air box etc.
    However, as part of stripping it down and dismantling things in the kitchen, I’ve discovered that the thermostat itself is completely seized and the head valves are significantly out. Also, air filter stinking of exhaust fumes, making me think, in light of further residue in the nearside inlet manifold, that it may not have been gasket related? What are your thoughts?
    I wouldn’t change what I’ve done in removing the head...I’ve learned so much and the valves are going to need sorting anyway.

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    59440D96-38B0-4B3C-B99E-32DB01F6F180.jpeg

    3EB3B055-5544-4A95-A22E-22D2E04BA87D.jpeg
     
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  2. StuarT595

    StuarT595 Active Member

    Nov 19, 2020
    204
    43
    South West UK
    I’ve wiped the sealing component of the gasket in the above last two images, and the ones below, just for a closer look.
    Many thanks for all your thoughts!
    Clearly the water channels need sorting!

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    03AC0283-799E-4644-8D20-F099189A71CE.jpeg
     
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  3. Herman66

    Herman66 Active Member

    Dec 28, 2019
    194
    43
    Dorset, U.K
    Out of my depth here but when the front cylander rocker cover gasket blew on my old HD Low Rider I had oil seepage near the front exhaust port.
    You would think if a gasket has blown that oil would be a sure sign ?
     
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  4. StuarT595

    StuarT595 Active Member

    Nov 19, 2020
    204
    43
    South West UK
    Many thanks for your ideas, much appreciated. I think a head gasket can fail in many ways...ingress of water into oil and/or vice versa...combustion gases into water and or oil, etc...which is why I’m uncertain. I would however, given the ‘idea’ that the water was blowing, that I’d be expecting the sealing rings around the combustion chambers to have breached...unless it was simply the seized thermostat?
    I know no more than that, and certainly far too inexperienced to know whether the above gasket has failed?
     
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  5. dilligaf

    dilligaf Guest

    I’m pretty sure that someone in the past on here had this problem and it was indeed traced back to the thermostat :(
    Had a look for it but can’t find it anywhere unfortunately :(
    You’re that far into now though that doing the valves etc definitely will be of benefit and changing the fluids is always a good idea :)
    Good luck mate and keep us posted :)
     
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  6. freck

    freck Elite Member

    May 4, 2017
    1,719
    750
    Preston, Lancs, UK
    It’s often difficult to tell if the gasket has failed.
    When I did my Daytona the gasket looked fine, there were no obvious signs of where leakage was occurring, yet I knew for certain that combustion gasses were leaking into the water jacket.
    I changed the gasket and to be certain had the head skimmed (only a few thou) and have never had a problem since. I’d also highly recommend that you reseal the liners as they don’t seem to have much sealant on them from the factory, and it’s recommended in the workshop manual.

    Also, don’t be too concerned about the rusty colour of the coolant and waterways; they’re all like that! Just make sure to give the system a good flush out when it’s all back together, and keep on top of coolant changes going forward; these bikes are very susceptible to problems caused by a sub-optimal cooling system.

    Good luck with the rebuild :)
     
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  7. StuarT595

    StuarT595 Active Member

    Nov 19, 2020
    204
    43
    South West UK
    Many thanks, dilligaf, appreciate you looking.
    As you say, the valves would’ve needed sorting anyway...maybe even need a couple changing?? We’ll see where we’re at after cutting them back in :)
     
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  8. StuarT595

    StuarT595 Active Member

    Nov 19, 2020
    204
    43
    South West UK
    Many thanks, Freck...top info., really good to know it isn’t always obvious.
    I haven’t checked the head for warp yet...I’m going to borrow an engineers’ edge tomorrow at the garage (taking the car in for MOT so perfect timing).
    I always thought OHC engines that run the camshafts in ‘shells’ cast into the head itself, couldn’t be skimmed? Good to know a couple of thou off has worked for you :)
    Will definitely be pulling and resealing the liners, I’ve made a puller from 2 x 3” drain plugs...looking forward to trying it out.
     
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  9. Adie P

    Adie P Crème de la Crème

    Jul 7, 2018
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    I'm no mechanic or engineer but I have replaced a head gasket on a Hillman Imp (long time ago, mind!) and, from what I can recall, there were clear and obvious signs of "blow by" on the gasket where the flame rings were breached. The gasket in your pictures seems to show no signs of a similar breach so, if I were a betting man, my money would go on the horse called "not the gasket"!

    So, why the similar sounding, gasket failure tell-tale symptoms? Poor starting and rough running are classic symptoms of valve clearance issues. You mention that the "valves were out" - does that mean the clearances were not in spec.?

    You've said the thermostat was seized - presumably closed, which would tend to lead to overheating or at least running very hot and maybe pressure in the cooling system and coolant loss.

    From the pictures I'd say that the head needs a thorough clean - preferably professional hot tank immersion, then compressed air dried. Search for a local engine reconditioning company and ask if they do head cleaning - either chemical or hot tank. I believe full immersion in coke (as in cola) works well if you're doing it yourself and helps remove some of the scale in the waterways.

    I'd also suggest from looking at the colour of that coolant that the whole cooling system will need to be throroughly backflushed and cleaned and the water pump is going to need to be inspected and possibly replaced - wouldn't be surprised if that's seized.

    I wish you luck with it - you've probably overcome the worst challenge with that head bolt removal!

    Cue The Carpenters .........?
     
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  10. StuarT595

    StuarT595 Active Member

    Nov 19, 2020
    204
    43
    South West UK
    ‘We’ve only just begun...’ :)
    Great stuff, Adie...you’re right on all your points, and the water pump is on the list for inspection.
    Yes, I did mean out of spec., nearly all the inlet valves were tight, unable to take a feeler gauge at all.
    Could I just ask what you mean by backflush? I had it in my mind to reassemble everything and run the bike with a coolant cleaner/descaler of some description, before changing it for an appropriate antifreeze/coolant...it that what you mean?
    Really appreciate your post, thank you.
     
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  11. Ddodge80

    Ddodge80 New Member

    Jan 17, 2021
    20
    3
    Pacolet sc
    In my past experiences no matter what kind of engine im working on i have found it best to do as much preliminary checking as possible before tear down.
    1 compression check all cylinders
    2 leak down test all cylinders
    3 pressure test cooling system
    4 install pressure test gauge on radiator run engine watch gauge for a minute or two
    To see if getting cylinder pressure
    5 check oil pressure
    It helps to narrow down where the problems are before taking the engine apart
     
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  12. Ddodge80

    Ddodge80 New Member

    Jan 17, 2021
    20
    3
    Pacolet sc
    In my past experiences no matter what kind of engine im working on i have found it best to do as much preliminary checking as possible before tear down.
    1 compression check all cylinders
    2 leak down test all cylinders
    3 pressure test cooling system
    4 install pressure test gauge on radiator run engine watch gauge for a minute or two
    To see if getting cylinder pressure
    5 check oil pressure
    It helps to narrow down where the problems are before taking the engine apart
     
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  13. StuarT595

    StuarT595 Active Member

    Nov 19, 2020
    204
    43
    South West UK
    Many thanks for that, a definite checklist to return to if I ever face this again.
    The only consolation I have is that the valves need regrinding, and I’ve learned a great deal along the way about my new ride (if/when I get it going properly) :)
     
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  14. Ddodge80

    Ddodge80 New Member

    Jan 17, 2021
    20
    3
    Pacolet sc
    Find a good compitante machine shop to help you. A good way to check your valve now that head is off.
    Fill port with water watch for leak at valve face then use blow gun blow compressed air around the edge of valve face watch for bubbles in port. If it cant hold that back it definitely wont seal out cylinder pressure.
    Good luck on your repair keep us posted.
     
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  15. Ddodge80

    Ddodge80 New Member

    Jan 17, 2021
    20
    3
    Pacolet sc
    Oh i almost forgot after you get the machine back together.
    It's a good practice to go ahead and do a compression check write it down.
    Then you can check it during your services
    To compare what it is. Gives you a refrence point helps see issues before they leave you stranded.
     
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  16. StuarT595

    StuarT595 Active Member

    Nov 19, 2020
    204
    43
    South West UK
    Many thanks again...will definitely look into that...really wish I’d checked it before dismantling :worried:
     
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  17. Tricky-Dicky

    Tricky-Dicky Crème de la Crème

    Dec 12, 2016
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    If you still have some of the old coolant run a sniffer test on it that's a sure fire way to tell if there are combustion gases in the coolant, otherwise it can be pretty difficult to tell but by the state of your coolant I am not surprised that the thermostat has seized and that will give very similar symptoms.
     
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  18. StuarT595

    StuarT595 Active Member

    Nov 19, 2020
    204
    43
    South West UK
    Many thanks, TD...will try and give the remaining sludge a sniff.
    I feel I should add, in view of the unloved coolant, that I’ve only recently acquired the bike as an unknown from auction :)
    So here’s a million dollar question...do I clean my coolant system with, or without, my new thermostat in place?
     
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  19. Yorkshireman

    Yorkshireman Crème de la Crème

    Dec 12, 2015
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    I’d say without. It won’t open unless with very hot water so you’d only get to flush as far as the stat in either direction and you don’t want to dislodge anything that could get stuck in it and cause a blockage. Even fully open when the engine is up to temperature it could be considered to be a restriction in the flow of the coolant and easily blocked.
    Good work so far, best of luck with the repairs/rebuild.
     
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  20. Adie P

    Adie P Crème de la Crème

    Jul 7, 2018
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    Morning Stuart. Sorry I missed this last night.

    If the valve clearances had closed up completely then there's a very strong chance that that will be the cause or a major part of the poor running/starting issues.

    In terms of backflushing, it will be worth your while removing the rad. and flushing it through via the outlet at the bottom - so the reverse direction to normal flow. If you're taking the water pump off then that will be cleaned up anyway so I'd guess an initial run with a cleaner descaler should be OK. I'm sure if that's not wise then someone with more experience will chime in on that.

    I'd definitely consider having the head professionally cleaned though - the coolant is doing most of its work here so that's where the passageways need to be clear and open.

    Good luck with it all.
     
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